1. Field of the Invention
The invention relates to a power-on signal transmitting system and a power-on signal transmitting method and, more particularly, to a power-on signal transmitting system and a power-on signal transmitting method capable of utilizing an idle wiring to transmitting a power-on signal.
2. Description of the Prior Art
In the information exchange process between electronic devices, designers and users are always seeking for lower cost, higher speed and better stability from the information exchange. In practical applications, we try to elevate the usage efficiency of the signal cable with all possibilities, and to maintain the quality of service (QoS) of the signal exchange at the same time.
There are several kinds of cables serving as the medium of the signal exchange between electronic devices. For example, coaxial cable, Small Computer System Interface (SCSI) cable, Serial Attached SCSI (SAS) cable, Advanced Technology Attachment (ATA) cable, Serial ATA (SATA) cable and High Definition Multimedia Interface (HDMI) cable are able to function in applications of communication, video on demand (VOD) and digital information computing. That to utilize these cables in information transmitting has its advantages of low cost, stability and adaptability to different purposes.
Please refer to FIG. 1 and FIG. 2. FIG. 1 is a schematic diagram illustrating a signal transmitting system 1 between electronic devices in prior art. FIG. 2 is a schematic diagram illustrating a wiring allocation of a signal cable 14 in FIG. 1. As shown in FIG. 1, the signal transmitting system 1 comprises an electronic device 10, an electronic device 12 and a signal cable 14. For example, the electronic device 10 can be a control unit of a personal computer, and the electronic device 12 can be a CD-ROM drive. Because there are demands for signal exchanging between the electronic device 10 and the electronic device 12, the cable 14 is used for forming a coupling relationship between the electronic device 10 and the electronic device 12.
The electronic device 10 has a signal process unit 100. On the other hand the electronic device 12 has a signal process unit 120. These two signal process units (100, 120) are used for handling, receiving, transmitting and converting messages between the electronic device 10 and the electronic device 12.
The cable 14 includes a plurality of wirings corresponding to demands for signal exchanging between the control unit of the PC and the CD-ROM drive in this case. The cable 14 in FIG. 2, for example, is a Mini SAS 4X cable. Following the definition of pin order, the cable 14 includes wirings PINA1˜PINA13 (from the electronic device 12 to the electronic device 10) and wirings PINB1˜PINB13 (from the electronic device 10 to the electronic device 12).
Take the wiring PINB1, the wiring PINB2 and the wiring PINB3 for demonstration. The wiring PINB2 and the wiring PINB3 form a differential pair of information wirings, for transmitting an information signal from the electronic device 10 to the electronic device 12. The wiring PINB1 is used for providing a reference level corresponding to the differential information signal via the wiring PINB2 and the wiring PINB3. In other word, the wiring PINB1 is a reference wiring corresponding to the wiring PINB2 and the wiring PINB3.
However, the electronic device 12 (e.g. CD-ROM) is not always at a power-on state. In some cases, the electronic device 12 is off by default. When a user operates the electronic device 10 (e.g. PC) and he needs the function from the electronic device 12, a power-on signal must be transmitted by the electronic device 10 to the electronic device 12, for activating and enabling the electronic device 12.
In this embodiment, the information wirings of the wiring PINB2 and the wiring PINB3 can be assigned to connect with a power-on signal generator for exclusively transmitting the power-on signal. However, the wiring PINB2 and the wiring PINB3 are limited to transmit only the power-on signal in this case. Therefore, after the electronic device 12 is power-on, the wirings (PINB2 and PINB3) are going to be idle during the power-on period of the electronic device 12, such that the efficiency of the wiring usage is decreased.
In another embodiment, the information wirings of the wiring PINB2 and the wiring PINB3 can be assigned to connect with the signal process unit 100 and the power-on signal generator at the same time. It utilizes the single pair of the wiring PINB2 and the wiring PINB3 to achieve two goals, which are to transmit the information signal and to transmit the power-on signal. However, the demands for the quality of the signal are elevated nowadays. The information signal is usually transmitted at a high-frequency with precisely low amplitude. Therefore, even though it can maintain the efficiency by inserting a fork circuit on the wirings (PINB2, PINB3) for branch-connecting to the power-on signal generator, but on the other hand it sacrifices the quality of the information signal through the wirings (PINB2, PINB3) as trade-off.
The invention discloses a power-on signal transmitting system and a power-on signal transmitting method, to solve aforesaid problems.